茉莉酸信号途径介导三七抗茄腐镰刀菌的分子机理研究

Panax notoginseng is a highly valued medicinal plant in China. The root rot is the major disease of P. notoginseng caused by some pathogenic fungi, which seriously impair the production and quality of raw material of P. notoginseng. Our previous study indicated that the Fusarium solani was the leading causal agent for the root rot of P. notoginseng, meanwhile, exogenous application of methyl jasmonate (MeJA) on root of P. notoginseng conferred resistance to F. solani. The molecular mechanism on resistant defense response of P. notoginseng induced by jasmonic acid (JA) will be revealed through RNA-Seq and gene expression profile analysis in the following study, and the cross talk in several defense-related signaling pathways of P. notoginseng during response to F. solani will be analyzed. Then the resistance-related genes, which respond the JA, will be isolated from P. notoginseng, and their expression patterns after inoculation with F. solani as well as treatment with several signaling molecules will be obtained. Subsequently, the functional characterization of several resistance-related genes will be performed using the reverse genetics techniques. The implement of this project will be helpful in further understanding the molecular interaction between P. notoginseng and F. solani. The present project aims to elucidate the molecular mechanism of resistant defense response of P. notoginseng mediated by JA signaling pathway and the crosstalk in several defense-related signaling pathways during infection of F. solani. Moreover, the results of this study will supply some theoretic knowledges for exogenous regulation of disease resistance in P. notoginseng with JA or other signaling molecules involved in defense response. In addition, the resistance-related genes will be applied to develop novel P. notoginseng cultivars with strong resistance to F. solani using the methods of molecular breeding.

三七(Panax notoginseng)是我国的传统名贵中药材。根腐病是三七的主要真菌病害，严重危害三七药材的产量和品质，茄腐镰刀菌(Fusarium solani)是三七根腐病的重要致病菌。我们前期研究发现外源茉莉酸甲酯预处理可显著增强三七对茄腐镰刀菌的抗性，本项目拟通过转录组测序及基因表达谱分析研究茉莉酸信号途径调控三七对茄腐镰刀菌抗性防卫反应的分子机制；探讨茉莉酸介导三七与茄腐镰刀菌的不亲和互作过程中多种防卫相关信号途径间的分子交谈；克隆响应茉莉酸的三七抗病相关基因，分析它们的表达特性，并验证其功能。该项目的实施可深入认识三七与茄腐镰刀菌的分子互作，揭示茉莉酸信号途径介导三七抗茄腐镰刀菌的分子机理及多种信号途径在三七应对茄腐镰刀菌防卫反应中的分子交谈，从而为利用茉莉酸或其它信号分子提高三七对根腐病的抗性奠定理论基础。此外，获得的抗病相关基因可为三七的分子育种提供理论和物质基础。

三七(Panax notoginseng)是我国的传统名贵中药材。根腐病是三七的主要真菌病害，严重危害三七药材的产量和品质，茄腐镰刀菌(Fusarium solani)是三七根腐病的重要致病菌。前期研究发现外源茉莉酸甲酯预处理可显著增强三七对茄腐镰刀菌的抗性，为了揭示茉莉酸信号途径调控三七抗茄腐镰刀菌防卫反应的分子机制，本项目进行了茉莉酸甲酯预处理三七受茄腐镰刀菌侵染过程的转录组测序分析，并测定了内源信号分子的含量，发现外源茉莉酸预处理上调了三七中茉莉酸、水杨酸、乙烯、过氧化氢四种信号分子的含量，并且四种信号途径均响应茄腐镰刀菌的入侵，相关基因不仅受外源茉莉酸甲酯的诱导，而且在茄腐镰刀菌侵染过程中表达水平进一步上升，可见外源茉莉酸处理激活防卫相关信号途径从而大大提高三七对根腐病菌茄腐镰刀菌的抗性。本研究通过转录组测序及基因表达谱分析从三七中发掘一系列响应茉莉酸的抗病相关基因，并采用反向遗传学技术验证了两个抗菌肽基因PnSN1、PnDEFL1以及几个病程相关蛋白基因PnPR10-3、PnCHI1、PnGlu1的功能。从三七中分离了一个促分裂原活化蛋白激酶激酶基因PnMAPKK1，转入烟草中过表达显著提高了对茄腐镰刀菌的抗性，并且PnMAPKK1的过表达上调了转基因烟草中茉莉酸和水杨酸的生物合成，几个茉莉酸/水杨酸信号途径基因在转基因烟草中的表达水平明显提高，显然，促分裂原活化蛋白激酶信号途径也参与茉莉酸介导的三七对茄腐镰刀菌的防卫反应。此外，从三七中分离了Dirigent基因家族的七个基因，其中PnDIR1在烟草中过表达上调了木质素、木脂素生物合成相关基因的表达量，同时提高了木质素的积累量，并增强了烟草对茄腐镰刀菌的抗性。可见三七Dirigent基因家族成员受茉莉酸信号途径的调控，参与三七与茄腐镰刀菌的分子互作。本研究揭示了三七与茄腐镰刀菌的分子互作，研究了茉莉酸信号途径介导三七抗茄腐镰刀菌的分子机理及多种防卫相关信号途径在三七受茄腐镰刀菌侵染过程中的分子交谈，为利用茉莉酸等信号分子提高三七对根腐病的抗性提供理论基础。